Multiple patterning refers to technologies developed for photolithography to enhance the feature density. In double patterning, a lithography process is enhanced to produce double the expected number of features. Techniques to achieve double patterning include a lithography-etch, lithography-etch approach that requires, as the name suggests, two exposures and two etch operations. A second technique is a lithography-freeze technique that requires only one etch operation and uses a chemical modification process to ‘freeze’ the exposed/developed resist before undergoing a second resist coat and exposure step. Because the freeze uses a chemical modification of the first exposed/developed resist, it is not adversely affected by subsequent lithography processing. Although requiring only a single etch operation, like the lithography-etch, lithography-etch technique, the lithography-freeze technique requires two exposures. Another approach is the usage of spacer-based patterning, which, although using a single exposure, involves multiple processing steps.